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<div class="refentry" lang="en"><a name="id103831-bb" id=
"id103831-bb"></a>
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<div class="refnamediv">
<h2><img src="figs/python.gif" alt="(Python)"><span class=
"refentrytitle">Function kamada_kawai_spring_layout</span></h2>
<p>boost::kamada_kawai_spring_layout &mdash; Kamada-Kawai spring
layout for connected, undirected graphs.</p>
</div>
<h2 xmlns:rev=
"http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class=
"refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev=
"http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class=
"refsynopsisdiv">
<pre class="synopsis">
<span class="bold"><b>template</b></span>&lt;<span class=
"bold"><b>typename</b></span> Topology, <span class=
"bold"><b>typename</b></span> Graph, <span class=
"bold"><b>typename</b></span> PositionMap, <span class=
"bold"><b>typename</b></span> WeightMap, <span class=
"bold"><b>typename</b></span> T,
         <span class=
"bold"><b>bool</b></span> EdgeOrSideLength, <span class=
"bold"><b>typename</b></span> Done, <span class=
"bold"><b>typename</b></span> VertexIndexMap,
         <span class=
"bold"><b>typename</b></span> DistanceMatrix, <span class=
"bold"><b>typename</b></span> SpringStrengthMatrix,
         <span class=
"bold"><b>typename</b></span> PartialDerivativeMap&gt;
  <span class="type"><span class=
"bold"><b>bool</b></span></span> kamada_kawai_spring_layout(<span class="bold"><b>const</b></span> Graph &amp; g, PositionMap position,
                                  WeightMap weight,
                                  <b>const</b> Topology&amp; space,
                                  <span class=
"emphasis"><em>unspecified</em></span> edge_or_side_length, Done done,
                                  <span class=
"bold"><b>typename</b></span> property_traits&lt; WeightMap &gt;::value_type spring_constant,
                                  VertexIndexMap index,
                                  DistanceMatrix distance,
                                  SpringStrengthMatrix spring_strength,
                                  PartialDerivativeMap partial_derivatives);
<span class="bold"><b>template</b></span>&lt;<span class=
"bold"><b>typename</b></span> Topology, <span class=
"bold"><b>typename</b></span> Graph, <span class=
"bold"><b>typename</b></span> PositionMap, <span class=
"bold"><b>typename</b></span> WeightMap, <span class=
"bold"><b>typename</b></span> T,
         <span class=
"bold"><b>bool</b></span> EdgeOrSideLength, <span class=
"bold"><b>typename</b></span> Done, <span class=
"bold"><b>typename</b></span> VertexIndexMap&gt;
  <span class="type"><span class=
"bold"><b>bool</b></span></span> kamada_kawai_spring_layout(<span class="bold"><b>const</b></span> Graph &amp; g, PositionMap position,
                                  WeightMap weight,
                                  <b>const</b> Topology&amp; space,
                                  <span class=
"emphasis"><em>unspecified</em></span> edge_or_side_length, Done done,
                                  <span class=
"bold"><b>typename</b></span> property_traits&lt; WeightMap &gt;::value_type spring_constant,
                                  VertexIndexMap index);
<span class="bold"><b>template</b></span>&lt;<span class=
"bold"><b>typename</b></span> Topology, <span class=
"bold"><b>typename</b></span> Graph, <span class=
"bold"><b>typename</b></span> PositionMap, <span class=
"bold"><b>typename</b></span> WeightMap, <span class=
"bold"><b>typename</b></span> T,
         <span class=
"bold"><b>bool</b></span> EdgeOrSideLength, <span class=
"bold"><b>typename</b></span> Done&gt;
  <span class="type"><span class=
"bold"><b>bool</b></span></span> kamada_kawai_spring_layout(<span class="bold"><b>const</b></span> Graph &amp; g, PositionMap position,
                                  WeightMap weight,
                                  <b>const</b> Topology&amp; space,
                                  <span class=
"emphasis"><em>unspecified</em></span> edge_or_side_length, Done done,
                                  <span class=
"bold"><b>typename</b></span> property_traits&lt; WeightMap &gt;::value_type spring_constant = typename property_traits&lt; WeightMap &gt;::value_type(1));
<span class="bold"><b>template</b></span>&lt;<span class=
"bold"><b>typename</b></span> Topology, <span class=
"bold"><b>typename</b></span> Graph, <span class=
"bold"><b>typename</b></span> PositionMap, <span class=
"bold"><b>typename</b></span> WeightMap, <span class=
"bold"><b>typename</b></span> T,
         <span class=
"bold"><b>bool</b></span> EdgeOrSideLength&gt;
  <span class="type"><span class=
"bold"><b>bool</b></span></span> kamada_kawai_spring_layout(<span class="bold"><b>const</b></span> Graph &amp; g, PositionMap position,
                                  WeightMap weight,
                                  <b>const</b> Topology&amp; space,
                                  <span class=
"emphasis"><em>unspecified</em></span> edge_or_side_length);
</pre></div>
<div class="refsect1" lang="en"><a name="id822881" id=
"id822881"></a>
<h2>Where Defined</h2>
<a href=
"../../../boost/graph/kamada_kawai_spring_layout.hpp">boost/graph/kamada_kawai_spring_layout.hpp</a>

<h2>Description</h2>
<p>This algorithm&nbsp;[<a href=
"bibliography.html#kamada89">57</a>] performs graph layout (in two
dimensions) for connected, undirected graphs. It operates by
relating the layout of graphs to a dynamic spring system and
minimizing the energy within that system. The strength of a spring
between two vertices is inversely proportional to the square of the
shortest distance (in graph terms) between those two vertices.
Essentially, vertices that are closer in the graph-theoretic sense
(i.e., by following edges) will have stronger springs and will
therefore be placed closer together.</p>
<p>Prior to invoking this algorithm, it is recommended that the
vertices be placed along the vertices of a regular n-sided polygon
via <a href="circle_layout.html"><tt>circle_layout</tt></a>.</p>
<p><b xmlns:rev=
"http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision"><span class="term">
Returns</span></b>: <tt class="computeroutput">true</tt> if layout
was successful or <tt class="computeroutput">false</tt> if a
negative weight cycle was detected or the graph is
disconnected.</p>

<h2>Parameters</h2>
IN: <tt>const Graph&amp; g</tt>
<blockquote>
  The graph, whose type <tt>Graph</tt> must model the
  <a href="VertexListGraph.html">VertexListGraph</a>,
  <a href="EdgeListGraph.html">EdgeListGraph</a>, and
  <a href="IncidenceGraph.html">IncidenceGraph</a> concepts. The
  graph must be undirected and connected. <br>
  <b>Python</b>: This parameter is named <tt>graph</tt> in Python.
</blockquote>

OUT: <tt>PositionMap position</tt>
<blockquote>
  This property map is used to store the position of each vertex.  The
  type <tt>PositionMap</tt> must be a model of <a
  href="../../property_map/doc/WritablePropertyMap.html">Writable Property
  Map</a>, with the graph's vertex descriptor type as its key type and
  <tt>Topology::point_type</tt> as its value type.<br>

  <b>Python</b>: The position map must be a <tt>vertex_point2d_map</tt> for
  the graph.<br>
  <b>Python default</b>: <tt>graph.get_vertex_point2d_map("position")</tt>
</blockquote>

IN: <tt>weight_map(WeightMap w_map)</tt>
<blockquote>
  The weight or ``length'' of each edge in the graph. The weights
  must all be non-negative, and the algorithm will throw a
  <a href="./exception.html#negative_edge"><tt>negative_edge</tt></a>
  exception is one of the edges is negative.
  The type <tt>WeightMap</tt> must be a model of
  <a href="../../property_map/doc/ReadablePropertyMap.html">Readable Property Map</a>. The edge descriptor type of
  the graph needs to be usable as the key type for the weight
  map. The value type for this map must be
  the same as the value type of the distance map.<br>
  <b>Default:</b>  <tt>get(edge_weight, g)</tt><br>

  <b>Python</b>: Must be an <tt>edge_double_map</tt> for the graph.<br>
  <b>Python default</b>: <tt>graph.get_edge_double_map("weight")</tt>
</blockquote>

IN: <tt>const Topology&amp; space</tt>
<blockquote>
The topology used to lay out the vertices.  This parameter describes both the
size and shape of the layout area, as well as its dimensionality; up to three
dimensions are supported by the current implementation.  Topologies are
described in more detail
(with a list of BGL-provided topologies) <a href="topology.html">in separate
documentation</a>.
</blockquote>

IN: <tt>EdgeOrSideLength edge_or_side_length</tt>
<blockquote>
Provides either the unit length <tt class= "computeroutput">e</tt> of
an edge in the layout or the length of a side <tt
class="computeroutput">s</tt> of the display area, and must be
either <tt class= "computeroutput">boost::edge_length(e)</tt> or <tt
class= "computeroutput">boost::side_length(s)</tt> , respectively.
<b>Python</b>: In Python, this value always refers to the side length
and may only be a <tt>double</tt>.
</blockquote>

IN: <tt>Done done</tt>
<blockquote>
A 4-argument function object that is passed the current
value of delta_p (i.e., the energy of vertex <tt class=
"computeroutput">p</tt> ), the vertex <tt class=
"computeroutput">p</tt> , the graph <tt class=
"computeroutput">g</tt> , and a boolean flag indicating whether
<tt class="computeroutput">delta_p</tt> is the maximum energy in
the system (when <tt class="computeroutput">true</tt> ) or the
energy of the vertex being moved.
<b>Default</b>: <a href=
"layout_tolerance.html"><tt class=
"computeroutput">layout_tolerance</tt></a> instantiated over the
value type of the weight map.<br>
<b>Python</b>: Any callable Python object with an appropriate signature suffices.
</blockquote>

IN: <tt>typename property_traits&lt;WeightMap&gt;::value_type spring_constant</tt>
<blockquote>
The constant multiplied by each spring's strength.
Larger values create systems with more energy that can take longer
to stabilize; smaller values create systems with less energy that
stabilize quickly but do not necessarily result in pleasing
layouts.<br>
<b>Default</b>: 1.
</blockquote>

IN: <tt>VertexIndexMap index</tt>
<blockquote>
As a mapping from vertices to index values between 0 and
<tt class="computeroutput">num_vertices(g)</tt> .<br>
<b>Default</b>:<tt class="computeroutput">get(vertex_index,g)</tt>.
    Note: if you use this default, make sure your graph has
    an internal <tt>vertex_index</tt> property. For example,
    <tt>adjacency_list</tt> with <tt>VertexList=listS</tt> does
    not have an internal <tt>vertex_index</tt> property.
   <br>
<b>Python</b>: Unsupported parameter.
</blockquote>

UTIL/OUT: <tt>DistanceMap distance</tt>
<blockquote>
This parameter will be used to store the distance from every vertex to
every other vertex, which is computed in the first stages of the
algorithm. This value's type must be a model of <a
href="BasicMatrix.html"><tt>BasicMatrix</tt></a> with value type equal to
the value type of the weight map.<br>
<b>Default</b>: A vector of vectors.<br>
<b>Python</b>: Unsupported parameter.
</blockquote>

UTIL/OUT: <tt>SpringStrengthMatrix spring_strength</tt>
<blockquote>

This matrix will be used to store the strength of the spring between
every pair of vertices. This value's type must be a model of <a
href="BasicMatrix.html">BasicMatrix</a> with value type equal to the
value type of the weight map.<br>
<b>Default</b>: A vector of vectors of the value type of the weight map.<br>
<b>Python</b>: Unsupported parameter.
</blockquote>

UTIL: <tt>PartialDerivativeMap partial_derivatives</tt>
<blockquote>
A property map that will be used to store the partial derivatives of
each vertex with respect to the vertex's current coordinates.
coordinates. This must be a
<a href="../../property_map/doc/ReadWritePropertyMap.html">Read/Write
Property Map</a> whose value type is <tt>Topology::point_difference_type</tt>.
The default is an iterator property map built using the graph's vertex index
map.<br>
<b>Default</b>: An <tt>iterator_property_map</tt> created from
an <tt>std::vector</tt> of <tt>Topology::point_difference_type</tt>.<br>
<b>Python</b>: Unsupported parameter.
</blockquote>

<b>Python</b> IN: <tt>bool progressive</tt>
<blockquote>
  When <tt>false</tt>, performs layout of the graph on a circle before
  running the Kamada-Kawai algorithm. If <tt>true</tt>, the algorithm
  is executing starting with the vertex configuration in
  the <tt>position</tt> map.<br>
  <b>Default</b>: <tt>False</tt>.
</blockquote>

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<td nowrap>Copyright &copy; 2004, 2010 Trustees of Indiana University</td>
<td><a href="http://www.boost.org/people/doug_gregor.html">Douglas Gregor</a>,
Indiana University (dgregor -at cs.indiana.edu)<br>
<a href="https://homes.cs.washington.edu/~al75">Andrew Lumsdaine</a>, Indiana
University (<a href=
"mailto:lums@osl.iu.edu">lums@osl.iu.edu</a>)</td>
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